Abstract

Method Retrospective case—control study of 234 patients who
died within 1 year of hospital discharge, matched for age, gender, diagnosis
and admission period with 431 controls. Odds ratios for identified risk
factors were calculated using conditional multiple logistic regression.

Conclusions Continuity of contact may reduce suicide risk.
Discontinuity of care from a significant professional is associated with
increased risk of suicide.

Suicide is a major cause of death in mental illness, increased risk being
associated with all diagnoses except dementia
(Harris & Barraclough,
1997). Reducing suicide among patients with severe mental illness
was a target in Health of the Nation
(Department of Health, 1992).
Accurate prediction of risk is difficult
(Allebeck et al, 1986;
Appleby, 1992) and little is
known about the protective or disruptive effect of mental health care.
Although risk is highest in the month after discharge
(Goldacre et al,
1993; Geddes & Juszczak,
1995), the incidence of suicide is low. The sensitivity,
specificity and positive predictive value of known risk factors is low, and
therefore the number of false-positives (patients perceived as high risk who
do not commit suicide) is high (Goldstein
et al, 1991). The Wessex Recent In-Patient Suicide Study
(WRISS) is a retrospective case—control study designed to test the
hypotheses that certain personal and clinical characteristics can predict
increased risk and that continuity of care after discharge reduces risk of
suicide.

METHOD

Sample size calculation

A 2:1 control—case ratio was chosen to increase the power of the
study. A standard calculation at a significance level of 0.05 and a power of
80%, based on an odds ratio of 1.5, assuming a breakdown in continuity of care
of 40% in living patients and 50% in deceased patients, gave a sample size of
600 living controls and 300 deceased in-patients.

Identification of recently discharged psychiatric patients

Every resident of Hampshire, Dorset, Wiltshire and the Isle of Wight
(Wessex) on whom a suicide (ICD-9 E950-59) or open verdict (ICD-9 E980-89,
excluding E9888) was given in the years 1988-1997 was identified from official
mortality files and coroners' registers
(King, 1983). These deaths are
collectively referred to as suicides; all open verdict deaths were considered
as potential suicides, because previous findings suggest that this gives a
more accurate figure for overall suicides
(Abed & Baker, 1998), and
open verdicts are included within the Health of the Nation targets. Every
inquest file was inspected and 373 suicides (including 92 open verdicts (25%))
were identified who died before discharge or within a year of discharge from
psychiatric in-patient treatment.

Ethical approval was obtained to inspect the case notes of discharged
recent psychiatric patients admitted to a hospital in the Wessex region, and
matched control patients. Recent in-patients admitted to hospitals outside
Wessex, to military or naval hospitals or to a special (high-security)
hospital were excluded. Data were extracted from medical case notes by one
psychiatrist (J.M.A.S.) and recorded on a specifically designed pro forma
under the headings: Admission history; Demographic information (including
legal and de facto marital status); Psychiatric history; Medical
history; Index admission; Discharge data; Communication with GP; Treatment at
admission and at death/follow-up; Last contact; Status of arranged psychiatric
services at death/follow-up; Continuity of contact; and Changes in personnel
after discharge. Two key variables were defined: whether or not there had been
a break in continuity of contact and whether or not there had been a change in
key personnel. Continuity of care was assessed by the number of days a patient
had been ‘out of contact’, as measured by the interval between the
date of a missed appointment, or self-discharge, and the date of next contact.
Key personnel included keyworker, consultant or out-patient doctor.

To clarify possible ambiguities in the collection and interpretation of
data, the research team compiled a manual of operationally defined criteria to
which to refer. A test—retest exercise of 12 sets of notes was
undertaken 12 months after the original pro forma had been completed. Kappa
was calculated for every variable on the questionnaire, but only 105 variables
were included in the a priori analysis. The result of the
test—retest exercise showed that the kappa correlation between the two
ratings was excellent (68%; κ>0.8) or very good (16%;
0.6<κ<0.8) in the vast majority of responses. None of the
variables for which kappa was <0.2 (very poor) was included in the
variables entered into the multiple regression model.

Matching of control patients

Each discharged index patient suicide was matched with two controls using
the following sequential criteria: gender; age (age of index patient ±
10 years but not crossing adolescent/old age service boundaries); psychiatric
diagnosis (schizophrenia and schizophrenia-like disorders, non-psychotic
affective disorders and ‘residual’ diagnoses); ward type; and
admission date. The two patients, satisfying the above criteria, whose
admission dates were nearest that of the index patient (within 2 months either
side) were selected. If only one suitable match could be made within this
period, then a single control patient was used. If no match was admitted
within 2 months, the time was extended in either direction until the closest
match of the same diagnostic group was found. Patients in the
‘residual’ diagnosis group were matched as closely as possible
within ICD-9 codes 300-316. Every index patient was matched with at least one
control. The follow-up period for each control was the same number of days as
the number of days from discharge to the event leading to death (ELD) for the
index patient.

Statistical procedures

Multiple conditional logistic regression
(Collett, 1991) was carried out
in STATA 6 (Stata Corp, 1999).
The resulting odds ratios (ORs) for a rare event (such as suicide) give an
approximate relative risk (Collett,
1991). A large amount of data were collected on each patient and
we identified 105 potential variables to analyse. The analysis proceeded in
two stages. The first was a hypothesis-testing approach in which variables
that had been specified a priori were included in a model, together
with potential confounders, also specified a priori. A
hypothesis-generating approach was also undertaken, in which a stepwise
backward elimination of variables, with probability for rejection set at 0.1,
was used to produce a parsimonious model.

Clinical application

Having defined those factors that showed statistical significance between
the two groups, and calculated the ORs, the sensitivity and specificity of
these factors were calculated in order to assess their utility within the risk
assessment process.

RESULTS

Sample

Of the 298 suicides identified, 11 non-Wessex admissions were excluded and
53 sets of case notes were untraceable
(Fig. 1). Case notes of both
controls were found for 84% index cases.

Follow-up period

Thirty-four per cent of the 234 discharged index patients died within 28
days of discharge, 61% within 3 months and 83% within 6 months.

Clinical characteristics

Sixty-one per cent of patients were admitted to old ‘mental
hospitals’, 36% to district general hospital psychiatric units and 2% to
private hospitals. Eighty-nine per cent were admitted to general psychiatric
open wards.

Although the index:control patients ratio was 1:1.84, the two groups were
well matched for gender, age and diagnosis. The male:female ratios are 1.67:1
(index) and 1.63:1 (controls). Mean ages of male index and control patients
were 42 (17-86) and 42 (18-82), and for the females 48 (15-87) and 47 (17-89)
years, respectively.

The diagnostic distribution of the index patients and controls differed
depending on the source of the diagnostic data (discharge register, discharge
summary, Patient Administration System (PAS) computer file or case notes) but,
irrespective of source, the two groups remained well-matched
(Table 1).

Results of conditional logistic regression analysis

Table 2 shows the results of
fitting a logistic regression model in which the three variables associated
with a breakdown in continuity of care were included, along with potential
confounders. This result was consistent for a variety of different
confounders: history of deliberate self-harm (DSH); admission because of
suicidal ideas; evidence of delusions/hallucinations, depressive symptoms,
feelings of hopelessness and evidence of misuse of non-prescribed substances
(excluding alcohol) at admission; and DSH during admission.

Continuity of contact

Although about 70% of both groups were in contact with the psychiatric
service at the time of ELD/follow-up, significantly more control patients had
remained in continuous care (no periods of time ‘out of contact’)
compared with index patients. Continuous care was associated with a decreased
risk of suicide.

Continuity of professional carers

A key professional being on leave, or leaving, at the time of the fatal act
was associated with a near 17-fold increase in suicide risk, but this occurred
in only 5% of the suicides.

Factors associated with changed risk of suicide

Table 3 shows the final
model, which explores the data set to find significant predictors of
suicide.

Social factors

The only social factor associated with increased suicide risk was living
alone, whereas admission from shared accommodation was associated with a
reduced risk. Shared accommodation included supported group homes and sharing
with friends: those living in unsupported hostels were considered to be living
alone.

Clinical factors

The two groups were similar in respect of Mental Health Act status at index
admission but differed in the reason for admission and information elicited on
history and mental state examination. A history of DSH, admission because of
suicidal ideation and mental state examination findings of hopelessness all
increased the risk of suicide. Neither a family history of suicide nor a
family history of mental illness changed the risk. Patients admitted with
psychotic features (delusions or hallucinations) or misuse of non-prescribed
substances occurred more frequently in the control group, despite being
matched for diagnosis, than in those who ultimately committed suicide
following their subsequent discharge.

Events during admission

Only the onset of new relationship difficulties was significantly
associated with an increased risk of suicide.

Events after discharge

Personal events

Loss of job between admission and ELD/follow-up was associated with a
sevenfold increase in suicide risk.

Cumulative effects

Of those who went on to commit suicide: 32% had at least four increased
suicide risk factors present, compared with only 9% of the control group; and
only 3.4% of the index cases had none of the identified risk factors, compared
with 15.5% of the control group. However, none of the index cases individually
had more than seven of the eleven factors present.

Sensitivity and specificity

As this is a case—control study, the positive predictive value (PPV)
of the risk factors cannot be ascertained because the prevalence is fixed at
33% (two controls per case), and the PPV depends on the prevalence of a
condition within the sample population.

DISCUSSION

This case—control study has identified eleven factors associated with
increased risk of suicide, and four factors associated with decreased risk, in
the year following discharge from psychiatric in-patient
care.⇓

Limitations

The study has three limitations. The first is that it relies on data
collected retrospectively from medical case notes that were not intended to be
used for research purposes. The fact that no information was recorded in
clinical notes in relation to a particular aspect of care does not mean that
the information was not known at the time. However, because decision-making in
health care is based on existing information, comprehensive and accurate
recording is a prerequisite for effective communication between professionals.
Data not available for this study were presumed not to be available to the
professionals treating the patient. As Bachrach
(1981) has argued,
communication or continuity of information, implies the existence of relevant
and adequate case records that are readily available to all involved providers
of health and social care.

The second limitation is that it was impossible to blind the research
fellow responsible for completing the data pro forma to the patient outcome.
To minimise possible bias, questions were made objective and were based only
on explicit information recorded in the case notes.

The third limitation is that many variables (105) were analysed but these
were identified as potential variables a priori. With any modelling
procedure some allowance should be made for multiple tests. Five of the
positive risk factors have a P value of ≤0.005 and so would remain
significant if a Bonferroni correction were applied.

Strengths

This study has the strength of being a large case—control study, with
a comprehensive sample drawn from a population of 2.9 million (1991 Census,
all ages; Office of Population Censuses
and Surveys, 1991). All patients received in-patient treatment
from at least one mental health facility within a single regional health
authority administrative area. Although the study was not prospective in
design, at the time of index admission and discharge all staff were in effect
‘blind’ as to which one of the three in-patients would die within
the following year.

Previous findings

A retrospective case—control study of 63 discharged in-patient
suicides (Dennehy et al,
1996) reported that ‘conventional’ risk factors, such
as unemployment and living alone, were as common among cases as controls.
These factors are characteristic of people with severe mental illness in
general and do not predict risk in individual psychiatric patients. A
subsequent report (Appleby et al,
1999) on 149 patients also reported no significantly increased
suicide risk associated with these variables.

New findings

In this larger study with two controls per index patient we found that nine
of the eleven increased-risk factors are associated with personal or clinical
characteristics, supporting our first hypothesis.

Readmission under the same consultant and continuous contact with the same
professionals are associated with decreased risk. This provides support for
the second hypothesis and emphasises the importance of continuity of both
contact and personnel, especially in vulnerable groups. However, this
statistically significant result may be an artefact of the retrospective
nature of the study, with bias in the recording of events with hindsight, and
would need to be evaluated in prospective studies.

Several potential factors may explain why patients admitted with psychotic
features (delusions/hallucinations) were significantly less likely to commit
suicide ultimately. The first is that patients with these symptoms may be
considered in need of hospital admission for treatment, without additionally
needing to be considered ‘at risk’ of suicide to justify their
hospital admission. Alternatively, the answer may lie in
‘treatability’ of severe mental illness and the consequent
reduction that this has on mortality.

It is often considered difficult to maintain contact with some patient
groups, particularly those with alcohol/drug dependence or a comorbid Axis II
disorder. However, in this study the ORs for continuity of care were not
altered significantly when analysed using these as a confounding factor. The
OR changed from 5.7 to 5.2 (95% CI 0.36-0.75). One of the key statements of
the National Confidential Inquiry into Suicide and Homicide by People with
Mental Illness is: “Suicides with alcohol or drug dependence or
personality disorder had the most disrupted pattern of care, including high
rates of loss of contact with services”
(Department of Health, 1999).
Our findings suggest that, when compared with controls with the same
diagnosis, this effect is less specific to the suicide group and more of a
reflection of general factors within this population.

The finding that misuse of nonprescribed substances appeared to be a
protective factor against suicide requires further exploration. Previous
studies have found high rates of suicide in those who misuse alcohol or drugs
(Appleby et al, 1997;
Harris & Barraclough,
1997). This group is more likely to receive a verdict of
accidental death rather than suicide
(King, 1990). Accidental death
verdicts were not included in this study and so rates were expected to be
lower. Alternatively, suicide rates in those who were not correctly identified
as having substance misuse might be particularly high, and the identification
and management of these conditions may be protective. A recent study of
in-patient suicides (Powell et
al, 2000) found that substance misuse was associated with a
reduced risk of suicide and postulated that patients admitted for these
problems were not as acutely ill as some other patients and do not have the
same suicide risk.

At index admission, the only significant social differences between the
index and control patients were in de facto marital status and living
alone. The only independent pre-admission clinical factor associated with an
increased risk of suicide was a history of DSH. This is consistent with the
findings of a similar case—control study (149 cases)
(Appleby et al,
1999).

Representativeness of sample

A comparison between the social, demographic and clinical characteristics
of the WRISS patients who died within 3 months of discharge and the
corresponding 519 suicides reported to the National Confidential Inquiry
(Department of Health, 1999)
suggests that the Wessex suicides are a representative group. The lower
prevalence of schizophrenia among WRISS patients may be because there are
relatively fewer urban conurbations in Wessex than in the rest of England and
Wales.

Implications for clinical practice

The highest risk of suicide in discharged in-patients occurs immediately
after leaving hospital, suggesting that flexible community support should be
made available at an early stage. However, the incidence of suicide in this
group is low: between 1 in 500 and 1 in 1000 of the patients discharged
(Geddes, 1999).

The 16-fold increase in risk when a significant professional was on leave,
or about to go on leave, at the time of the fatal act indicates that a break
in the continuity of the carer may be a final precipitating factor in
predisposed individuals. This is consistent with the
‘relationship’ element in continuity of care as described by
Bachrach (1981): “the
patient's ability to rely, over time, on having an association with a person
or persons who are interested in him/her and who respond to him/her on a
personal level”.

Information about the increased suicide risk associated with post-discharge
social events could be useful to general practitioners, who may feel that they
have little responsibility for the mental health of their patients if they are
currently under the care of psychiatric services. However, they are often
contacted and are frequently the last contact that the patient has with a
health professional prior to suicide
(King, 2001).

Awareness of the identified risk factors for suicide after discharge could
be used to structure risk assessments at discharge and at subsequent reviews.
The numerical values associated with these risk factors could allow serial
assessment of a current ‘risk score’ by health-care professionals
both when caring for psychiatric in-patients and when engaged in their
long-term follow-up. This score could become part of regular
multi-disciplinary discussions, with documentation of the score within the
Care Programme Approach process. Mental health services then could be
delivered in a flexible fashion, with increased intervention at times of
higher risk and lesser involvement during periods of low risk. However, there
will be a significant false-positive rate, which will have resource and
ethical consequences if treatment and discharge decisions are based solely
upon a ‘risk score’.

The low sensitivity and specificity of identified risk factors confirm the
findings of previous studies (Appleby
et al, 1999;
Department of Health, 1999).
Identifying which patients are at higher risk of suicide remains an inexact
science.

Clinical Implications and Limitations

CLINICAL IMPLICATIONS

In discharged patients, one-third of suicides occurred within the first
month after discharge.

It is possible to identify factors associated with the outcome of
suicide in recently discharged patients, but the utility of these factors
remains uncertain.

Continuity of contact may reduce suicide risk.

LIMITATIONS

Data were collected retrospectively from medical case notes that were
not originally intended for research purposes, and data collection was not
carried out blind to case—control status.

The sensitivity and specificity of the identified risk factors are
low.

Acknowledgments

Thanks are due to: Professor Andrew Stevens (Department of Public Health,
University of Birmingham), who helped to develop the protocol; Dr Sarah Goode,
who matched all the index patients with two controls and located the notes;
Lorna Campbell, for administrative support and data entry; and all the
coroners, clinicians and medical records staff, without whose cooperation this
study would not have been possible. The Research Support Subcommittee of the
University of Southampton provided some additional funding.

Footnotes

References

Abed, R.T. & Baker,I. (1998) A comparison
between the OPCS and coroner's data on suicide and undetermined deaths in an
English Health District. International Journal of Psychiatry in
Clinical Practice, 2,
209-214.